A new study shows being tired behind the wheel may be a bigger problem than previously thought.

The AAA study says 9.5 percent of crashes can be blamed on "drowsy drivers." That's a much-higher figure than previous studies, which relied on drivers "admitting" they fell asleep behind the wheel. 

The survey saw it happen firsthand. AAA put dashboard cameras in the cars of more than 3,500 drivers. Over several months, those drivers had 701 crashes.

"That figure was eye-popping to me as well because that's nearly a third of all the drivers we were tracking," says AAA spokesman Robert Sinclair. 

Back in 2011, a Nassau County police officer was killed on the Long Island Expressway by a driver who lost control of his flatbed truck. Although it was never proven in court, prosecutors said sleep deprivation was the cause because the driver allegedly admitted to only getting five hours of sleep before the crash. 

"Missing just two to three hours of sleep is a serious sleep deprivation situation and can leave a person in a condition similar to being drunk," says Sinclair. 

AAA recommends that anyone who is driving and feeling tired should pull over, get a cup of coffee and take a 20-minute nap.